The invention relates to a delivery device, by which small parts in the nature of studs, bushes and pins are delivered to a transportation channel from a sloping collection area, with a retaining and dividing wall, which stands approximately perpendicular, on one side of which the sloping collection area ends in an aperture at a distance from the retaining and dividing wall and along the other side of which is the transportation channel running at an incline to the horizontal, and with a strut in the form of a plate, also displaceable approximately perpendicularly along the retaining and dividing wall, which in its lower position is located approximately at the height of the end edge of the sloping collection area and in its upper position above the transportation channel, in such a way that small parts coming to rest on the retaining and dividing wall are carried along by the upper narrow side of the strut and are delivered into the transportation channel over the upper edge of the retaining and dividing wall.
A delivery device of this kind is known from operational practice. The small parts such as studs, bushes and pins arrive on the sloping surface from a magazine and come to a halt at the retaining and dividing wall still in a largely random arrangement. The strut travels upwards at regular intervals and takes the small parts located on its upper narrow side with it. The small parts located on the upper narrow side are by this time substantially aligned in their longitudinal direction. Once the upper edge of the strut has gone beyond the height of the retaining and dividing wall, a side infeed conveys the small parts over the upper edge of the retaining and dividing wall into the transportation channel located on the other side. The receiver profile of the transportation channel, i.e. the shape of its cross-section, is often a segment of a circle, the measurement of which approximately corresponds to that of the small parts to be transported. The small parts then slide in a kind of flat channel or trough, wherein the transportation channel vibrates. They are delivered therein to an application site.
In practice it has been found that the known delivery device is not free of defects. For instance, during the lifting movement of the strut individual small parts often fell back on to the sloping collection area in an erratic fashion. Or they were not reliably delivered to the transportation channel at the highest point of the strut. It had also proved desirable to be able to meter the exact number of small parts arriving in the transportation channel from the sloping collection area. This is the way to achieve as even a supply to the transportation channel as possible.
The object of the invention is therefore to create a delivery device of the kind initially mentioned, by which the small parts can be delivered to the transportation channel from the sloping collection area reliably and in amounts which can be exactly determined.
The delivery device is characterised in that the upper narrow side of the strut slopes diagonally downwards at least partially towards the retaining and dividing wall.
When the upper narrow side of the strut slopes obliquely downwards in the way described, in a lower position of the strut the small parts arrive in a kind of channel of acute-angled cross-section, which is formed by the perpendicular side face of the retaining and dividing wall on the one hand and by the obliquely running upper narrow side of the strut on the other hand. Small parts in the nature of studs, bushes and pins, which usually have a basically rotationally symmetrical shape, thus lodge themselves on the retaining and dividing wall in a substantially orderly fashion and with their axial direction running parallel to the retaining and dividing wall. If the strut is then driven upwards into an upper position, the obliquely designed upper narrow edge prevents the small parts from falling down and they roll with no further ado from the narrow side down into the transportation channel when the upper edge of the retaining and dividing wall has been passed. The delivery device according to the invention therefore works very reliably and it can be expected that the small parts, having reached the oblique upper narrow edge of the strut, will be reliably delivered into the transportation channel. The amount of small parts with which the transportation channel is supplied can therefore be set with great accuracy.
According to a further development of the invention it is provided that upwardly directed projections in the nature of pinnacles and gaps alternate with one another in the longitudinal direction of the upper narrow side of the strut. Preferably the slope directed obliquely downwards towards the retaining and dividing wall is only present in the gaps.
Thus, according to this further development not the whole upper narrow side of the strut is utilised to transport the small parts. In other words, the upwardly directed projections of the strut are not used for transporting the small parts. The number of small parts which are to arrive in the transportation channel can thus be varied.
A further improvement can occur if the projections slope obliquely upwards towards the retaining and dividing wall. In this way it is achieved that those small parts which are not to be taken along arrive back promptly and carefully on the sloping collection area and that the small parts are prevented from being left behind and falling down.
In order to make the best possible use of the transportation length of the strut, according to a further advantageous development the longitudinal extension of the gaps is to be a multiple of the longitudinal extension of the projections. Concretely it is preferable if the longitudinal extension of the gaps is three to five times the longitudinal extension of the projections.
To accommodate different types of small parts or to adapt to different amounts to be conveyed each time the strut is lifted, the strut could be changed each time. However, according to a further advantageous development it is preferably provided that a metering plate is joined on to the strut, in particular to the upper region of the strut, on which the gaps are left open and the projections are formed by bending upwards. In this case adapting to different types or numbers of small parts can be done by simple changing of the metering plate. The metering plate can, for example, be screwed to the strut for ease of changing.
So that the small parts move as easily and automatically as possible from the sloping collection area on to the upper narrow side of the strut when they come to rest on the retaining and dividing wall in the lower operating position of the strut, it is provided, according to yet another development, that in the lower position of the strut the higher edge of its upper narrow side is located approximately at the height of the adjacent end edge of the sloping collection area. The upper narrow side of the strut therefore becomes a continuation of the sloping collection area and facilitates the transition and the alignment of the small parts.
The invention also relates to a transportation channel in a device for transporting small parts in the nature of studs, bushes, pins and suchlike which are delivered to an application site from a store, the transportation channel having a receiver profile of such a kind that the small parts are conveyed on the transportation channel sliding substantially in the direction of their longitudinal axis. Transportation channels of this kind are known. In combination with the corresponding automatic transportation devices they serve in automatic assembly to deliver a large number of small parts, including, for example, screws, continuously to the assembly site. A known example is the automatic production of motor vehicles. The transportation channel can be sloping or driven by an oscillating conveyor. The receiver profile in the transportation direction, i.e. its cross-section, is often a segment of a circle, the measurement of which approximately corresponds to that of the small part to be transported. The small parts then slide in a kind of flat channel or trough.
The known transportation channels work reliably when the small parts to be conveyed have approximately the same cross-sectional shape and measurement over their whole length. Accordingly, the conveying of bushes with hexagonal or circular cross-section is particularly favourable. If, on the other hand, studs are to be conveyed which have portions of very varying diameter, these can no longer slide smoothly in the transportation channel. They then jump around and no longer slide smoothly in the transportation channel. To guarantee troublefree operation it is necessary to build in baffles for sorting the pins into the right position.
The difficulties mentioned arise, for example, with so-called earthing studs, with which earthing cables are fastened, for example, on the bodywork of motor vehicles or electrical appliances. The earthing studs consist of a shaft with a thread portion and a substantially cylindrical head. The thread portion is covered by a cap with a hexagonal outer shape. This cap, which can consist of a plastics material, for example, covers the thread of the earthing stud during lacquering and similar procedures. As the round head of the screw protrudes above the hexagonal cross-section of the covering cap, the result is a particularly uneven movement of the earthing studs on the transportation channel and this can cause unpleasant disturbances in the transportation procedure.
With the invention, in a generic transportation channel it is to be achieved that even small parts with a very varying cross-sectional shape and transverse measurement over their length can be reliably conveyed.
This aim of the invention is achieved in a generic transportation channel in that the transportation channel has a compound receiver profile. A compound receiver profile means that it is not determined only by one single geometric shape and by one single defining measurement, as is the case, for example, with a segment of a circle in the nature of a flat trough. A compound receiver profile can, for example, be formed by two circular arcs of different diameter or by a circular arc in combination with a polygonal contour.
With a development of the transportation channel of this kind the longitudinally differing regions of each individual small part are differently supported in the transportation channel. The small part is fixed better in the direction of its longitudinal axis and thereby also centred and is no longer inclined to tumble or jump around. As a result it glides better and baffles to sort the small parts into the right position are no longer needed. In this fashion reliable conveyance even of irregularly contoured small parts is achieved without additional devices, which would be complicated and expensive.
The improvement can in particular be made in that, according to a further development, the cross-section of the receiver profile is composed of at least two basic contours, each of which corresponds to one of several longitudinally differing cross-sectional shapes of the small part to be conveyed. In this way in an individual case particularly reliable guidance of the small part in the transportation channel is possible.
If, for example, screws with a cylindrical screw head are to be conveyed in the transportation channel, the transportation channel according to the invention can be further developed in that the receiver profile of the transportation channel is a segment of a circle starting from its upper side, out of which a segment of a circle of smaller diameter protrudes downwards. The continually conveyed screws then slide with their heads on the segment of a circle of larger diameter starting from the upper side, while the screw shank is guided through the segment of a circle of smaller diameter adjoining underneath. It is soon clear that screws guided in this way are no longer inclined to tumble or jump around, i.e., they avoid transverse movements on the transportation channel.
If, according to yet another development, it is provided that the receiver profile of the transportation channel is a segment of a circle starting from its upper side, out of which a rectangle protrudes at the bottom, the already mentioned earthing studs can therefore be particularly well transported. The cylindrical screw head of the earthing studs, which comprises the largest transverse measurement of this small part, then slides in the part of the receiver profile shaped like a segment of a circle, while the covering cap of the earthing stud, which comprises the smaller transverse measurement, engages with the outer part of a hexagonal side of a rectangular part of the receiver profile. The earthing studs, with their longitudinal axis slightly tilted downwards, are then located exactly in the longitudinal axis of the transportation channel. It is particularly advantageous for this, according to an additional further development, if the diameter of the segment of a circle is marginally larger than the largest diameter of the circular cross-section of the small part and if the width of the rectangle is marginally larger than the width of the polygonal cross-section of the small part. The transportation channel can consist of a longitudinal profile in the nature of a rail, from the upper side of which a longitudinal groove with a cross-section shaped like a segment of a circle starts and continues downwards in a rectangular groove.
The transportation channel can also consist of a flat part bent into a longitudinal profile.